Elamipretide · Bendavia · Szeto-Schiller Peptide 31
A mitochondria-targeted tetrapeptide that binds cardiolipin on the inner mitochondrial membrane, improving electron transport chain efficiency, reducing reactive oxygen species production and restoring ATP output. A foundational anti-aging compound.
SS-31 (elamipretide) is a synthetic tetrapeptide (4 amino acids) developed by Dr. Hazel Szeto that selectively accumulates in the inner mitochondrial membrane (IMM). It is one of the best-characterised mitochondria-targeted compounds and has received FDA Orphan Drug Designation for Barth Syndrome — a rare genetic mitochondrial disorder.
The mechanism of SS-31 centres on cardiolipin — a unique phospholipid found almost exclusively in the inner mitochondrial membrane. Cardiolipin plays a critical structural role in organising the electron transport chain complexes and maintaining optimal cristae structure. As cells age or become stressed, cardiolipin is damaged by reactive oxygen species (ROS), disrupting mitochondrial structure and function.
SS-31 binds directly to cardiolipin, stabilising its structure and the protein complexes associated with it. This has several downstream effects: improved electron transport chain efficiency (more ATP per oxygen molecule); reduced electron leak and therefore reduced ROS production; preservation of mitochondrial membrane potential; and protection against mitochondrial permeability transition pore opening which triggers cell death.
SS-31 has been studied across cardiac disease (heart failure, ischemia-reperfusion injury), renal disease, skeletal muscle aging, neurodegeneration and general aging models. In cardiac research, it has demonstrated significant improvements in cardiac output, reduced myocardial damage post-ischemia and restoration of mitochondrial function in failing hearts.
In aging research, SS-31 has reversed age-associated declines in skeletal muscle mitochondrial function, restored exercise capacity in old mice to levels seen in young mice, and demonstrated broad anti-aging effects consistent with the theory that mitochondrial dysfunction is a primary driver of aging.
SS-31 has more human clinical data than most compounds in this space. Completed trials include Phase II studies in heart failure with preserved ejection fraction (HFPEF), Barth Syndrome and acute kidney injury. Results have been mixed — showing clear biomarker improvements but variable clinical endpoint results, leading to the discontinuation of some programs and continuation of others.
In the longevity research context, SS-31 is valued for its ability to address mitochondrial dysfunction — widely considered one of the primary hallmarks of aging. Stacking it with NAD+ precursors and MOTS-c creates a synergistic mitochondrial support protocol targeting multiple aspects of age-related energy decline.